The objective of the proposed research is to study the mechanisms associated with transduction in free standing lateral line and other hair cell organs. Specifically, we propose to investigate the dynamic relationships between water flow, cupula motion, receptor potentials, membrane conductance changes, synaptic processes, and afferent nerve responses. We also propose to directly test in lateral line organs the postulated relationship between the morphological orientation and directional sensitivity of hair cells. Established electrode techniques will be employed in recording from and staining hair cells intracellularly and in recording nerve impulse activity. Conductance changes will be determined by standard bridge circuitry or by voltage clamp methods. Synaptic activation in the absence of mechanical stimulation will be produced by galvanic current. We propose to control stimuli, analyze receptor potentials, and reduce nerve spike data by means of a small on-line computer facility. We also propose to study the relationship of cupular motion to nerve responses in the semicircular canals, particularly with respect to the origin of neural adaptation. The roles of various ions in hair cell transduction and synaptic function will be explored by observing the effects on spontaneous and evoked activity of varying concentrations of these ions in the extracellular fluids.